Table_1_Hatchery tanks induce intense reduction in microbiota diversity associated with gills and guts of two endemic species of the São Francisco River.XLSX

The São Francisco River (SFR), one of the main Brazilian rivers, has suffered cumulative anthropogenic impacts, leading to ever-decreasing fish stocks and environmental, economic, and social consequences. Rhinelepis aspera and Prochilodus argenteus are medium-sized, bottom-feeding, and rheophilic fishes from the SFR that suffer from these actions. Both species are targeted for spawning and restocking operations due to their relevance in artisanal fisheries, commercial activities, and conservation concerns. Using high-throughput sequencing of the 16S rRNA gene, we characterized the microbiome present in the gills and guts of these species recruited from an impacted SFR region and hatchery tanks (HT). Our results showed that bacterial diversity from the gill and gut at the genera level in both fish species from HT is 87% smaller than in species from the SFR. Furthermore, only 15 and 29% of bacterial genera are shared between gills and guts in R. aspera and P. argenteus from SFR, respectively, showing an intimate relationship between functional differences in organs. In both species from SFR, pathogenic, xenobiont-degrading, and cyanotoxin-producer bacterial genera were found, indicating the critical pollution scenario in which the river finds itself. This study allowed us to conclude that the conditions imposed on fish in the HT act as important modulators of microbial diversity in the analyzed tissues. It also raises questions regarding the effects of these conditions on hatchery spawn fish and their suitability for restocking activities, aggravated by the narrow genetic diversity associated with such freshwater systems.

圣弗朗西斯科河（SFR），作为巴西主要河流之一，长期遭受累积的人为影响，导致鱼类资源持续减少，并引发环境、经济和社会层面的诸多后果。Rhinelepis aspera和Prochilodus argenteus为中等体型、栖息于底层且喜好流动水域的鱼类，源自SFR，深受上述影响之害。鉴于其在手工艺渔业、商业活动和保护关切中的重要性，这两种物种均被作为繁殖和补充种群的目标。通过16S rRNA基因的高通量测序，我们对源自受影响SFR区域和孵化池（HT）的这些物种的鳃部和肠道中的微生物群进行了表征。研究结果显示，来自孵化池的两种鱼类鳃部和肠道在属水平上的细菌多样性比源自SFR的物种减少了87%。此外，来自SFR的R. aspera和P. argenteus的鳃部和肠道之间仅有15%和29%的细菌属是共有的，这表明器官功能差异之间存在着密切的联系。在SFR的两种鱼类中，均发现了病原性细菌、异源生物降解细菌和蓝藻毒素产生细菌属，这表明河流正处于一个关键的污染情境中。本研究使我们得出结论，孵化池中对鱼类施加的条件是分析组织中微生物多样性重要调节因素。同时，它也引发了关于这些条件对孵化池繁殖鱼的影响及其是否适合补充种群活动的疑问，尤其是考虑到与这些淡水系统相关的遗传多样性狭窄。